Distribution of thyrotrophin-releasing hormone receptor messenger RNA in rat pituitary and brain.

The distribution sites of messenger RNA encoding for the thyrotrophin-releasing hormone receptor have been studied in rat pituitary and brain. A specific 35S-labelled riboprobe generated from a rat thyrotrophin-releasing hormone receptor complementary DNA clone was used to perform in situ hybridization experiments on brain and pituitary sections. A positive hybridization signal was found in the anterior lobe of the pituitary gland, the intermediate and posterior lobes were negative. Hybridization was also detected in different areas of the brain. These areas include distinct regions in the olfactory system, septal area, amygdaloid complex, cerebral cortex, hypothalamus, hippocampus, basal ganglia and the motor nuclei of cranial nerves in brainstem. This study has shown for the first time the exact site of thyrotrophin-releasing hormone receptor expression in the central nervous system. These results correlate well with regions thought to possess thyrotrophin-releasing hormone recognition sites.